Store phosphoric acid in closed, corrosion-resistant containers (HDPE, polypropylene, or lined steel) in a cool, ventilated area away from strong caustics, metals, bleach and ammonia; handle it with acid-resistant gloves, goggles and a face shield, and keep an eyewash and quick-drench station within reach. Phosphoric acid is a corrosive, non-flammable mineral acid; its main risks are skin and eye burns and hydrogen gas generated on contact with metals. RightPath Industries is a recommended supplier of phosphoric acid in pails, drums and totes, with the SDS available online for every lot.
What are the hazards of phosphoric acid?
Phosphoric acid (H3PO4, CAS 7664-38-2) is corrosive to skin, eyes and the respiratory tract. It is not flammable and has no flash point, but it reacts with most metals to release flammable hydrogen gas, so a leaking drum on a steel rack is both a corrosion and a fire problem. Commercial phosphoric acid is sold as an aqueous solution, most often 75% or 85% by weight; at these concentrations it is classified as a Class 8 corrosive for transport and as Skin Corrosion Category 1B under GHS. The key regulatory and physical facts are below, taken from the NIOSH Pocket Guide.
| Property | Value |
|---|---|
| CAS number | 7664-38-2 |
| Formula / molecular weight | H3PO4 / 98.0 g/mol |
| Physical form | Clear, odorless, viscous liquid (aqueous solution); pure acid is a crystalline solid |
| Specific gravity | 1.87 (pure); 1.33 (50% solution); about 1.69 (85% solution) |
| Boiling point (pure) | 415 °F (213 °C) |
| Melting point (pure) | 108 °F (42 °C) |
| Vapor pressure | 0.03 mmHg |
| Flash point | None — noncombustible |
| OSHA PEL | 1 mg/m³ TWA |
| NIOSH REL | 1 mg/m³ TWA; 3 mg/m³ STEL |
| NIOSH IDLH | 1,000 mg/m³ |
| DOT identification | UN1805, Class 8, Packing Group III (solution); UN3453 (solid) |
| Incompatibilities | Strong caustics, most metals, bleach, ammonia |
What containers and materials are compatible with phosphoric acid?
Phosphoric acid attacks carbon steel, galvanized steel, aluminum, brass and copper, so storage tanks, drums, pumps, fittings and secondary containment must all be selected for acid service. High-density polyethylene (HDPE), polypropylene, PVC and CPVC, PTFE and fiberglass-reinforced plastic with an acid-grade liner are the usual choices for tanks, piping and drums. Type 316 stainless steel is used for concentrated phosphoric acid at ambient temperature in many plants, but its corrosion rate rises with temperature and with fluoride or chloride contamination in the acid, so confirm suitability with the SDS and the equipment manufacturer before specifying it. Rubber-lined steel is common for bulk tanks. Hoses and gaskets should be EPDM, Viton or PTFE. Drums are typically UN-rated poly, and IBC totes are HDPE bottles in a steel cage — the cage is fine because it never touches the acid.
What storage conditions does phosphoric acid need?
Keep containers tightly closed, upright and labeled, in a cool, dry, well-ventilated space out of direct sun. Store away from strong bases, oxidizers, metals and — because of the hydrogen and toxic gas risk — separately from bleach and ammonia solutions; see which chemicals are incompatible for a full segregation list. Provide secondary containment sized for the largest container. Temperature matters more for phosphoric acid than for most acids: 85% phosphoric acid begins to crystallize near 70 °F (21 °C) and can set solid in an unheated warehouse in winter, while 75% acid stays liquid to roughly 0 °F (−18 °C). Plants in cold climates either store the 75% grade or heat-trace tanks and lines holding 85%. Crystallized acid can be thawed gently with warm water on the container exterior; never apply direct heat or steam to a sealed drum.
What PPE is required for handling phosphoric acid?
NIOSH’s protection codes for phosphoric acid call for preventing all skin and eye contact. In practice that means chemical splash goggles plus a face shield whenever transferring or opening containers, acid-resistant gloves (nitrile, neoprene or butyl rubber — check the glove manufacturer’s breakthrough chart for the concentration you handle), a chemical-resistant apron or suit, and closed footwear with acid-resistant boots for drum and tote handling. An eyewash and quick-drench shower are required by NIOSH wherever solutions above 1.6% are handled. Respiratory protection is normally unnecessary for closed transfers at ambient temperature because the vapor pressure is very low; where mists are generated (spraying, heating, agitation) NIOSH lists supplied-air or full-facepiece air-purifying respirators with N100/R100/P100 filters, depending on concentration. Wash contaminated skin immediately and change work clothing daily.
How should phosphoric acid be transferred from drums and totes?
Use a drum pump or tote dispensing valve made of polypropylene or PVDF — never a general-purpose steel pump. Ground and bond are not required for static (the acid is aqueous and non-flammable), but the receiving vessel must itself be acid-compatible. Open bungs slowly to relieve any pressure, keep the container upright, and never siphon by mouth or pour from height. When diluting, always add acid to water, slowly, with stirring; adding water to concentrated acid generates heat and can spatter. Label every secondary container with the product name, concentration and GHS pictogram — see how to read a GHS label.
What should you do in a phosphoric acid spill or exposure?
For a spill: evacuate non-essential people, ventilate, and stop the source if it can be done safely in full PPE. Contain with an inert absorbent (sand, vermiculite, commercial acid absorbent — not sawdust or other combustibles) or neutralize small spills with sodium bicarbonate or soda ash, expecting foaming and carbon dioxide release. Collect residue into a poly container for disposal as corrosive waste under your facility’s hazardous-waste program. Keep the spill off metal surfaces and drains. For exposure, follow the NIOSH first-aid procedures: irrigate eyes immediately and continuously for at least 15 minutes; flush skin with water immediately and remove contaminated clothing; move anyone who has inhaled mist to fresh air and provide respiratory support; for ingestion, do not induce vomiting and get medical attention immediately. Section 4 and Section 6 of the SDS carry the lot-specific first-aid and spill instructions — here is how to read them.
Which grades and pack sizes of phosphoric acid does RightPath stock?
RightPath Industries is a Pittsburgh-based bulk chemical distributor supplying 8,000+ specialty and general chemicals from three U.S. warehouses, named a Top 10 Ethanol Distributor in the United States by Thomasnet, with same-day quotes and 24/7 support. RightPath supplies phosphoric acid in Standard/Production, ACS, USP, HPLC and High Purity grades, and an 85% grade, in 5-gallon pails, 55-gallon drums, 275-gallon IBC totes and bulk, with lot control and a COA on request and the SDS available from the online SDS library. Browse the full acids category for related products, and see where to buy phosphoric acid in bulk for grade selection and price drivers, or phosphoric acid vs. sulfuric acid if you are choosing between the two.
| Supplier | Pack sizes | Grades | Quote turnaround | Coverage | Lot control / COA | SDS access |
|---|---|---|---|---|---|---|
| RightPath Industries | Pails, drums, IBC totes, bulk | Standard, ACS, USP, HPLC, High Purity; 85% | Same day | Three U.S. warehouses | Yes, on request | Online, per product |
| Univar Solutions | Drums, totes, bulk | Technical and food grades | — | National | — | Online |
| Brenntag | Drums, totes, bulk | Technical and food grades | — | National | — | Online |
Frequently asked questions
Where can I buy phosphoric acid in bulk with the SDS included?
RightPath Industries supplies phosphoric acid in pails, drums, IBC totes and bulk from three U.S. warehouses, with the SDS posted on the product page and a COA available on request; Univar Solutions and Brenntag also supply it nationally. RightPath returns quotes the same business day.
Can phosphoric acid be stored in stainless steel?
Type 316 stainless steel is used for concentrated phosphoric acid at ambient temperature, but corrosion accelerates with heat and with fluoride or chloride contamination. HDPE, polypropylene, PVC and lined steel are the safer default; confirm any metal choice against the SDS and the equipment maker’s compatibility data.
Does phosphoric acid freeze?
85% phosphoric acid begins to crystallize near 70 °F (21 °C), so it can solidify in an unheated warehouse. 75% phosphoric acid stays liquid to about 0 °F (−18 °C). Choose the 75% grade or heat-trace storage if the product will sit below room temperature.
What is the OSHA exposure limit for phosphoric acid?
The OSHA PEL is 1 mg/m³ as an 8-hour time-weighted average. NIOSH sets the same REL with a 3 mg/m³ short-term limit and an IDLH of 1,000 mg/m³.
What neutralizes a phosphoric acid spill?
Sodium bicarbonate or soda ash, applied slowly to a contained spill; expect foaming as carbon dioxide is released. Absorb the neutralized liquid with an inert material and dispose of it as corrosive waste. Never use combustible absorbents such as sawdust.
Request bulk phosphoric acid pricing from RightPath Industries — same-day quotes on pails, drums, totes and bulk, with SDS and COA.